Whitefly [Kanakarajiella cardamomi David and Subr David and Sundararaj

Infestation of whitefly was a rare phenomenon in cardamom till 1980s, its sporadic occurrence was limited to Nelliampathy and Vandiperiyar areas (Anonymous, 1980;

Butani, 1984). Its infestation is now noticed at many places in Udumpanchola and Peermedu taluks of Idukki District of Kerala and lower Pulneys of Tamil Nadu. The species of whiteflies reported to infest cardamom are Dialeurodes cardamomi David and Subr. (presently known as Kanakarajiella cardamomi (David and Subr.) David and Sundarraj (1993), Aleuroclava cardamomi (David and Subr.), Aleurocanthus sp., Bemesia tabaci (Genn.) and Cockerella diascoreae Sundararajan and David (Selvakumaran and Kumaresan, 1993); however, only K. cardamomi is destructive to cardamom (Fig. 8.7).

Nymphs of the insect are found in large numbers only on the adaxial surface of leaves and adults on different parts of the plant. Both suck the plant sap resulting in yellowing and gradual drying up of plants leading to drastic decline of yields and in certain cases complete destruction of the plants. Nymphs produce a sugary secretion, which drop on lower leaves, where sooty moulds develop, obstructing normal light interception and photosynthesis (Gopakumar etal., 1988b). Adult is a small soft-bodied insect about 2 mm in length having two pairs of white wings. Male is smaller than female. Though adults are not active fliers, they fly about from plant to plant or even small distances, and are often swept off by wind, which is a major mode of migration of the pest. Gopakumar et al. (1988b) and Selvakumaran and Kumaresan (1993) studied the biology of the pest. Adults reproduce by parthenogenetic and sexual methods. Adults live for 7—8 days, females lay about 115 eggs singly which are inserted into the stomata on the adaxial leaf surface by means of short sub-terminal stalk. Eggs are pale yellow when freshly laid and turn brown before hatching. Parthenogenetic eggs develop exclusively into females. The first instar, called crawler, is ovate-elongate, greenish-yellow and wanders on the leaf surface in search of suitable feeding sites. Later it anchors itself with its piercing stylet at a suitable place on the leaf, from

Images White Fly Cardamom
Figure 8.7 White fly of cardamom: a nymphs and pupal exuvia of cardamom whitefly, Kanakarajiella Cardamomi.

where it sucks up plant sap. It becomes sedentary and grows to a dorso-ventrally-flattened structure possessing 14 pairs of marginal setae. The second instar is deep yellow, elliptical in shape and possesses paired anterior and posterior setae. Third instar is yellow, sub-elliptical, with better-developed legs and anterior and posterior abdominal spiracles. Fourth instar is distinct from other nymphal stages due to the presence of a pair of small red eyes and deep yellow-tinged slightly convex body. Its margin is irregularly crenulate. Puparia, which adhere to the leaves after adult emergence, appear as scabby patches on lower surface of affected leaves. Its life-cycle is completed within 43-60 days. Adults of the pest are very much attracted towards yellow colour and this behaviour is well exploited for trapping them on a yellow surface coated with sticky material. Yellow sticky traps made of metal sheets painted yellow and coated with castor oil has been recommended to trap and kill adult white-flies (Kumaresan et al., 1993). Spraying neem oil 0.5 per cent + triton or sandovit 0.5 per cent on under surface of leaves, 2-3 times at fortnightly intervals during periods of pest infestation, is effective against nymphs (Gopakumar and Kumaresan, 1991). Acephate 0.075 per cent, Ethion 0.1 per cent and Triazophos 0.4 per cent were found equally effective against the nymphs (Gopakumar et al, 1988a, 1988c; Kumaresan et al., 1993; Selvakumaran and Kumaresan, 1993).

Under natural conditions the pest has been found susceptible to a number of natural enemies such as predators like Mallada bonninensis, unidentified neuropteran, dipteran, coleopteran and mite; parasitoids such as Encarsia septentrionalis and E. dialeurodes, and a pathogen Aschersonia placenta (Selvakumaran and Kumaresan, 1993; Selvakumaran et al, 1996). Potential of these natural enemies as biocontrol agents of whiteflies is unexplored.

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